Stented prosthetic heart valve with variable stiffness and methods of use

ABSTRACT

A prosthetic heart valve including a stent frame and a valve structure. The valve structure is disposed within a lumen of the stent frame. The stent frame is configured to self-expand from a compressed condition for transluminal delivery. The stent frame has a lattice structure forming a tubular shape defining a circumference and a plurality of closed cells arranged to define a band exhibiting a variable radial stiffness. The prosthesis can be deployed such that the band applies a minimal force on to anatomical locations relating to the heart&#39;s conductive pathways. A region of the band otherwise having low radial stiffness is located at or over a conductive pathway upon final implant.

BACKGROUND

The present disclosure relates to prosthetic heart valves. More particularly, it relates to stented prosthetic heart valves and related methods of use.

Diseased or otherwise deficient heart valves can be repaired or replaced with an implanted prosthetic heart valve. Conventionally, heart valve replacement surgery is an open-heart procedure conducted under general anesthesia, during which the heart is stopped and blood flow is controlled by a heart-lung bypass machine. Traditional open-heart surgery inflicts significant patient trauma and discomfort, and exposes the patient to a number of potential risks.

More recently, minimally invasive systems and techniques have been developed to facilitate catheter-based implantation of the valve prosthesis in the beating heart, intending to obviate the need for the use of classical sternotomy and cardiopulmonary bypass. With transcatheter (or transluminal) techniques, a valve prosthesis is compacted for delivery in a catheter and then advanced to the heart, for example through an opening in the femoral artery, subclavian artery, aorta, or ventricular apex to access the aortic valve. The delivered prosthesis is then deployed in the annulus of the valve to be replaced.

The heart valve prosthesis employed with transcatheter procedures generally includes an expandable, multiple-level frame or stent that supports a valve body having two or more leaflets. The actual shape and configuration of any particular prosthetic heart valve is dependent to some extent upon the native shape and size of the valve being repaired (i.e., aortic valve, mitral valve, tricuspid valve, or pulmonary valve). In general, prosthetic heart valve designs attempt to replicate the functions of the valve being replaced, and the stent utilized with the prosthesis dictates the final size and shape. In addition, the stent serves to anchor the transcatheter valve prosthesis at or about the native annulus.

One type of transcatheter valve stent frame can be initially provided in an expanded or uncrimped condition, then crimped or compressed about a balloon portion of a catheter. The balloon is subsequently inflated to expand and deploy the prosthetic heart valve. With other stented prosthetic heart valve designs, the stent frame is formed to be self-expanding. With these systems, the valve stent is crimped down to a desired size and held in that compressed state within a sheath for transluminal delivery. Retracting the sheath from this valve stent allows the stent to self-expand to a larger diameter, fixating at the native valve site. With either of these types of percutaneous stented prosthetic heart valve delivery devices, conventional sewing of the prosthetic heart valve to the patient's native tissue is typically not necessary.

In order to achieve necessary, long term anchoring at the native valve site, the stent frame must provide and maintain an elevated hoop strength and resistance to radially collapsing or compressive forces. A prosthetic valve that is not adequately anchored in place to resist the forces of the constantly changing vessel wall diameter, and turbulent blood flow there through, may dislodge itself, or otherwise become ineffective. In light of these requirements, transcatheter prosthetic heart valve stent frame designs are premised upon structural robustness, sufficient radial hoop strength or stiffness, and high fatigue strength. Further, the size or length of the stent is desirably selected to ensure elevated interface with the native anatomy. Lattice-type stent frame designs have been found to be well suited to meet these requirements, and are conventionally formatted to have a repeating pattern of closely sized, shaped and arranged cells. It has been found, however, that the stented transcatheter prosthetic heart valve may contribute to cardiac pacing issues post implantation. For example, it is estimated that approximately 10-30% of self-expanding transcatheter aortic valve procedures require pacemaker implantation.

In light of the above, a need exists for a stented transcatheter prosthetic heart valve with reduced impact on the conductive pathways of the heart.

SUMMARY

Some aspects of the present disclosure relate to a prosthetic heart valve including a stent frame and a valve structure. The valve structure is disposed within a lumen of the stent frame. The stent frame is configured to self-expand from a compressed condition for transluminal delivery to a natural, expanded condition. The stent frame has a lattice structure forming a tubular shape defining a circumference. The lattice structure provides a plurality of closed cells arranged to define a band of closed cells extending about an entirety of the circumference, with the closed cells of the first band being equidistantly spaced from one another along the circumference. Further, the band is configured to have or exhibit a varying radial stiffness along the circumference in the natural condition. With this construction, the prosthetic heart valve can be deployed relative to the native anatomy such that the band applies a minimal force on to anatomical location(s) relating to the heart's conductive pathways. More particularly, a region of the band otherwise having or exhibiting low radial stiffness is located at or over a conductive pathway (e.g., conduction fibers of the left ventricular septum, SA node, Bundle of HIS, etc.), with the low radial stiffness region thus exerting a reduced force on the conductive pathway (as compared to the force exerted by other regions of the stent having a “normal” or elevated radial stiffness). Each of the closed cells includes a plurality of interconnected struts. In some embodiments, a dimension of at least one of the struts of the closed cells of the low radial stiffness region is less than a corresponding dimension of a corresponding strut of the closed cells of other regions of the band. In yet other embodiments, the band further includes a node body connecting two struts of each of the closed cells to one another, and a dimension of at least one of the node bodies of the low radial stiffness region is less than a corresponding dimension of each of the node bodies of other regions of the band.

Other aspects in accordance with principles of the present disclosure relate to a prosthetic heart valve having a stent frame and a valve structure. The valve structure is disposed within a lumen of the stent frame. The stent frame is configured to self-expand from a compressed condition for transluminal delivery to a natural, expanded condition. The stent frame has a lattice structure forming a tubular shape defining a circumference. The lattice structure provides a plurality of closed cells arranged to define first and second bands of closed cells each extending about an entirety of the circumference. The first band is located immediately longitudinally adjacent to the second band. In this regard, the first band is configured to have a varying radial stiffness along the circumference in the natural condition, and each of the closed cells of the second band are directly connected to a corresponding one of the closed cells of the first band. With this construction, the varying radial stiffness of the first band includes one or more regions of reduced radial stiffness that can be aligned with conductive pathways or tissue of the native valve anatomy.

Yet other aspects in accordance with principles of the present disclosure relate to a method of treating a native heart valve of a patient. The method includes delivering a prosthetic heart valve to the native heart valve. The prosthetic heart valve includes a stent frame maintaining a valve structure. The stent frame is configured to self-expand from a compressed condition to a natural, expanded condition. The stent frame has a lattice structure defining at least a first band of closed cells extending about an entirety of a circumference of the stent frame. The first band defines first and second regions, with the first region having a radial stiffness less than a radial stiffness of the second region. In this regard, the step of delivering the prosthetic heart valve includes maintaining the stent frame in the compressed condition within a delivery device. The prosthetic heart valve is then deployed from the delivery device into the native heart valve, including the stent frame self-expanding toward the natural condition. The first region (of reduced radial stiffness) is aligned with a desired anatomical location of the native heart valve. In some embodiments, the native heart valve is an aortic valve, and the desired anatomical location is along the left ventricular septum. In other embodiments, the desired anatomical location is a bundle of conduction fibers along the left ventricular septum.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a side view of a stented prosthetic heart valve in accordance principles of the present disclosure and in a normal, expanded condition;

FIG. 1B is a side view of the prosthetic heart valve of FIGS. 1A and 1 n a compressed condition;

FIG. 2A is an enlarged side view of a stent frame portion of the prosthetic heart valve of FIG. 1A;

FIG. 2B is a simplified schematic end view of the stent frame of FIG. 2A;

FIG. 3 is an enlarged, two-dimensional or unwrapped representation of a portion of the stent frame of FIG. 2A;

FIG. 4A is an enlarged side view of a strut component of a closed cell of the stent frame of FIG. 3, taken along the line 4A;

FIG. 4B is an enlarged side view of a strut component of another closed cell of the stent frame of FIG. 3, taken along the line 4B;

FIG. 4C is an enlarged side view of another strut component useful with the stent frame of FIG. 3;

FIG. 4D is an enlarged side view of another strut component useful with the stent frame of FIG. 3;

FIG. 5A is a cross-sectional, dissected illustration of an aortic valve and surrounding anatomy;

FIG. 5B illustrates the prosthetic heart valve of FIG. 1A implanted to the aortic valve of FIG. 5A;

FIG. 5C is a cross-sectional view of the human heart and identifies various conductive pathways; and

FIG. 6 illustrates, in simplified form, delivery and alignment of the prosthetic heart valve of FIG. 1A to a native valve.

DETAILED DESCRIPTION

As referred to herein, stented transcatheter prosthetic heart valve can assume a wide variety of different configurations, such as a bioprosthetic heart valve having tissue leaflets or a synthetic heart valve having polymeric, metallic or tissue-engineered leaflets, and can be specifically configured for replacing any of the four valves of the human heart. In general terms, the stented prosthetic heart valves of the present disclosure include a stent or stent frame maintaining a valve structure (tissue or synthetic), with the stent having a normal, expanded condition or arrangement and collapsible to a compressed condition or arrangement for loading within a delivery device. The stent frame is normally constructed to self-deploy or self-expand when released from the delivery device. For example, stents or stent frames are support structures that comprise a number of struts or wire segments arranged relative to each other to provide a desired compressibility and strength to the prosthetic heart valve. The struts or wire segments are arranged such that they are capable of self-transitioning from a compressed or collapsed condition to a normal, radially expanded condition. The struts or wire segments can be formed from a shape memory material, such as a nickel titanium alloy (e.g., Nitinol™). The stent frame can be laser-cut from a single piece of material, or can be assembled from a number of discrete components.

With the above understanding in mind, one simplified, non-limiting example of a stented prosthetic heart valve 20 in accordance with principles of the present disclosure is illustrated in FIG. 1A. As a point of reference, the prosthetic heart valve 20 is shown in a normal or expanded condition in the view of FIG. 1A; FIG. 1B illustrates the prosthetic heart valve 20 in a compressed condition (e.g., when compressively retained within an outer catheter or sheath). The prosthetic heart valve 20 includes a stent or stent frame 22 and a valve structure 24. The stent frame 22 can generally assume any of the forms mentioned above, and is generally constructed so as to be self-expandable from the compressed condition (FIG. 1B) to the normal, expanded condition (FIG. 1A). In other embodiments, the stent frame 22 can be configured for expansion from the compressed condition to the expanded condition via operation of a separate tool, such as a balloon (i.e., the stent frame 22 can be a balloon-expandable stent frame as known in the art).

The valve structure 24 can assume a variety of forms, and can be, for example, formed from one or more biocompatible synthetic materials, synthetic polymers, autograft tissue, homograft tissue, xenograft tissue, or one or more other suitable materials. In some embodiments, the valve structure 24 can be formed, for example, from bovine, porcine, equine, ovine and/or other suitable animal tissues. In some embodiments, the valve structure 24 can be formed, for example, from heart valve tissue, pericardium and/or other suitable tissue. In some embodiments, the valve structure 24 can include or form one or more leaflets 26. For example, the valve structure 24 can be in the form of a tri-leaflet bovine pericardium valve, a bi-leaflet valve, or other suitable valve. In some constructions, the valve structure 24 can comprise two or three leaflets that are fastened together at enlarged lateral end regions to form commissural points 28, with the unattached edges forming cooptation edges of the valve structure 24. The leaflets 26 can be fastened to a skirt (not shown) that in turn is attached to the stent frame 22. The upper ends of the commissural points 28 can define an inflow portion 30 corresponding to a first or inflow end 32 of the prosthesis 20. The opposite end of the valve structure 24 can define an outflow portion 34 corresponding to a second or outflow end 36 of the prosthesis 20.

With the exemplary construction of FIGS. 1A and 1B, the prosthetic heart valve 20 can be configured (e.g., sized and shaped) for replacing or repairing an aortic valve. Alternatively, other shapes are envisioned, adapted to mimic the specific anatomy of the valve to be repaired (e.g., the stented prosthetic heart valve of the present disclosure can alternatively be shaped and/or sized for replacing a native mitral, pulmonic, or tricuspid valve).

The self-expanding stent frame 22 is configured to generate a high radially expansive force (alternatively referred to as a chronic outward force) when forced to the compressed condition of FIG. 1B for self-deployment, and exhibit high resistance to radial compression (alternatively referred to as a radial resistive force or force required to compress the stent frame 22) once in the normal, expanded condition of FIG. 1A. It will be recognized that when implanted, the stent frame 22 will expand from the compressed condition toward the normal condition; however, the stent frame 22 will not fully attain the normal condition. Instead, the stent frame 22 is sized and shaped in accordance with the expected anatomy such that the stent frame 22 intimately contacts the native anatomy at a level of expansion less than the normal condition. In this way, the chronic outward force attribute of the stent frame 22 ensures that the stent frame 22 securely lodges or anchors against the native anatomy, with the stent frame 22 thus applying a force onto the native anatomy. This inherent characteristic of the stent frame 22 can also be referred to in terms of radial stiffness.

With this in mind, FIG. 2A illustrates the stent frame 22 in isolation. The stent frame 22 has a lattice structure that provides a plurality of closed cells 40 (several of which are referenced in FIG. 2A). The lattice structure collectively forms a tubular shape defining a circumference (best reflected by the schematic end view of FIG. 2B). The closed cells 40 are arranged about the circumference, and the lattice structure can be viewed as defining one or more circumferential bands of closed cells. For example, first, second and third circumferential bands 50-54 are identified in FIG. 2A. The stent frame 22 is configured such that a radial stiffness exhibited along the first band 50 (in at least the normal, expanded condition) varies along the circumference as described below. The radial stiffness exhibited along the second and third bands 52, 54 can be substantially uniform along an entirety of the circumference in some embodiments; alternatively, more than one circumferential band defined by the lattice structure of stent frame 22 have a varying radial stiffness along the circumference (e.g., the first and second bands 50, 52 can have the varying radial stiffness attributes described below). Regardless, the variable radial stiffness embodied by at least the first circumferential band 50 is configured to impart minimal or reduced force on contacted tissue upon implant of the stent frame 22, for example imparting less chronic outward force onto a native conduction fibers or bundle.

The variable radial stiffness of the first band 50 can be characterized by regions of differing radial stiffness. For example, in the view of FIG. 2B, a first region 60 and a second region 62 are identified. As a point of reference, FIG. 2B is a schematic end view of the stent frame 22 from the inflow end 32, illustrating the tubular nature of the stent frame 22 in the normal, expanded state, and generally reflects a location of the closed cells 40 along the first band 50. With this in mind, each of the regions 60, 62 consists of at least two circumferentially adjacent closed cells 40. The stent frame 22 is constructed such that the radial stiffness along the first region 60 is less than the radial stiffness along the second region 62. In this regard, the stent frame 22 can exhibit a constant radial stiffness along an entirety of the first region 60 or along an entirety of the second region 62, or the radial stiffness within the regions 60/62 can vary slightly, respectively. Regardless, the minimum radial stiffness at any location along the second region 62 is greater than the maximum radial stiffness along any portion of the first region 60. The elevated radial stiffness of the second region 62 (as compared to the radial stiffness of first region 60) is akin to that provided at other longitudinal locations along the stent frame 22 and is conventionally sufficient for anchoring the stent frame 22 at a native valve site. A maximum radial stiffness along the first region 60 is sufficiently less than the radial stiffness along the second region 62 by a level sufficient to not induce conditions on to native tissue that would otherwise contribute to a need for a pacemaker. For example, a maximum radial stiffness along the first region 60 can be at least 10% less, alternatively at least 20% less, alternatively at least 40% less, alternatively at least 60% less than a minimum radial stiffness along the second region 62.

As reflected by FIG. 2B, an arc angle of the second region 62 is greater than that of the first region 60, with the second region 62 serving to promote robust anchoring of the stent frame 22 to the native valve anatomy (along the first band 50). Thus, at least a majority of the closed cells 40 of the first band 50 are along the second region 62. By way of one non-limiting example, with embodiments in which the first band 50 includes eighteen of the closed cells 40, the second region 62 consists of at least ten, optionally at least twelve of the closed cells 40. Conversely, the first region 60 includes no more than four of the closed cells 40, alternatively two of the closed cells 40.

In some embodiments, the first band 50 can be further viewed as providing third and fourth regions 64, 66 as identified in FIG. 2B. The third and fourth regions 64, 66 represent transitions in radial stiffness from the elevated radial stiffness second region 62 to the low radial stiffness first region 60. The transition regions 64, 66 thus exhibit a radial stiffness less than that of the second region 62 but greater than that of the first region 60, and encompass a relatively small arc length or arc angle (as compared to the arc length or arc angle of the second region 62). By way of one non-limiting example, the transition regions 64, 66 can each consist of no more than four, alternatively two, of the closed cells 40. The transition regions 64, 66 minimize the possibility that the stent frame 22 will buckle or in-fold at the first region 60.

The low radial stiffness first region 60 can be generated in a variety of fashions. In more general terms, the closed cells 40 of the variable radial stiffness first band 50 are generally akin to, and follow the pattern of, other bands defined by the stent frame 22. Thus, the closed cells 40 of the variable radial stiffness first band 50 are uniformly and equidistantly spaced from one another along the circumference. That is to say, the low radial stiffness first region 60 does not omit a portion or entirety of any of the closed cells 40. In other embodiments, the variable radial stiffness first band 50 includes the same number of closed cells 40 as the immediately longitudinally adjacent second band 52, with each of the closed cells 40 of the second band 52 being directly physically connected to a corresponding closed cell 40 of the first band 50. By maintaining the closed cell pattern along an entirety of the circumference of the first band 50, the first band 50 will have minimal negative impact, if any, on an overall fatigue strength of the stent frame 22.

In some embodiments, the low radial stiffness first region 60 is generated by altering or reducing, but not eliminating, a geometric attribute of one or more of the structures otherwise generating one or more of the closed cells 40 and/or connections between the closed cells 40 of the first region 60. For example, FIG. 3 illustrates a portion of the stent frame 22 in a two-dimensional or “unwrapped” form (and in the compressed condition). For ease of explanation, the closed cells 40, and corresponding components thereof, of the low radial stiffness first region 50 are identified with the suffix “L” (e.g., the closed cells 40L), whereas the suffix “E” is utilized with structures of the second region 62 (e.g., the closed cells 40E). Each of the closed cells 40 of the first band 50 are connected to one another by a connector 70. Further, each of the closed cells 40 is formed or defined by a plurality of struts 72-78. For example, the closed cells 40E of the elevated stiffness second region 62 are each defined by struts 72E-78E. The first and second struts 72E, 74E are interconnected at a first node 80E, and the third and fourth struts 76E, 78E are interconnected at a second node 82E. A size and shape of each of the struts 72E-78E of the elevated stiffness closed cells 40E are identical or substantially identical (e.g., within 5% of a truly identical construction). The connectors 70 along the elevated radial stiffness second region 62 are also identical or substantially identical. While the closed cells 40L of the low stiffness first region 60 are each defined by struts 72L-78L interconnected by nodes 80L, 82L and are thus generally similar to the elevated stiffness cells 40E, at least one of the components 72L-78L, 80L, 82L, is not identical to the corresponding component 72E-78E, 80E, 82E of the elevated radial stiffness cells 40E. The low radial stiffness along the first region 60 is effectuated by altering a geometry of one or more of the struts 72L-78L and/or nodes 80L, 82L of one or more of the cells 40L, and/or one or more of the connectors 70L, along the first region 60.

For example, FIG. 4A illustrates one of the struts 72E of one of the elevated radial stiffness closed cells 40E (FIG. 3). The strut 72E can be viewed as having or defining a leading segment 90E, an intermediate segment 92E, and a trailing segment 94E. The leading segment 90E defines a length L_(LE) and a width W_(LE). The intermediate segment 92E similarly defines a length L_(IE) and a width W_(IE). The trailing segment 94E has a length L_(TE) and a width W_(TE). The leading segment 90E extends from a connector 70E (partially illustrated in FIG. 3B), and can taper in width W_(LE) to the intermediate segment 92E. The width W_(IE) of the intermediate segment 92E can be substantially uniform in extension from the leading segment 90E to the trailing segment 94E. The trailing segment 94E can have an increasing width W_(TE) in extension from the intermediate segment 92E to the corresponding node 80E (shown in partially in FIG. 4A). Finally, the node 80E has a height H_(NE) and a width W_(NE).

With the above geometric attributes of the strut 72E (or “elevated stiffness strut”) in mind, FIG. 4B illustrates one non-limiting example of a strut 72L (or “low stiffness strut”) of one of the low radial stiffness closed cells 40L in accordance with principles of the present disclosure. As a point of reference, the low stiffness strut 72L spatially corresponds with the elevated stiffness strut 72E of FIG. 4A (i.e., the struts 72E, 72L are both at the lower left quadrant of the corresponding closed cell 40E, 40L in FIG. 3). The low stiffness strut 72E has the same general shape and size as the elevated stiffness strut 72E, however a geometry of at least one of the segments 90L-94L differs from the corresponding segment 90E-94E of the elevated stiffness strut 72E. For example, the width W_(LL) of the leading segment 90L is less than the corresponding leading segment width W_(LE) of the elevated stiffness strut 72E. The reduction in mass reduces the radial stiffness of the low stiffness strut 72L (as compared to the radial stiffness associated with the elevated stiffness strut 72E). As a point of reference, the reduction in the width W_(LL) is exaggerated in FIG. 4B for ease of understanding. In actual practice, the leading segment width W_(LL) need only be slightly less than the normal width W_(LE). In other embodiments, the width W_(IL) of the low stiffness strut intermediate segment 92E can be less than the corresponding intermediate segment width W_(IE) of the elevated stiffness strut 72E. Alternatively or in addition, the width W_(TL) of the trailing segment 94L of the low stiffness strut 72L can be less than the width W_(TE) of the trailing segment 94E of the elevated stiffness strut 72E.

Another non-limiting embodiment of a low stiffness strut 72L1 in accordance with principles of the present disclosure is shown in FIG. 4C. A comparison with the elevated stiffness strut 72E of FIG. 4A reveals that the length L_(LL1) of the leading segment 90L1 is less than the length L_(LE) of the leading segment 90E of the elevated stiffness strut 72E, whereas the length L_(IL1) of the intermediate segment 92L1 is greater than the length L_(IE) of the elevated stiffness strut 72E (such that an overall length of the low stiffness strut 72L1 is the same as the overall length of the elevated stiffness strut 72E). The overall reduction in mass lessons the radial stiffness of the low stiffness strut 72L1 (as compared to the radial stiffness presented by the elevated stiffness strut 72E). Alternatively or in addition, the length L_(IL1) of the intermediate segment 92L1 can be less than that associated with the elevated stiffness strut 72E, and the length L_(TL1) of the low stiffness strut trailing segment 94L1 can be less or greater than that of the elevated stiffness strut 72E.

In yet other embodiments, the low stiffness struts of the present disclosure can incorporate both reduced width(s) and length(s). Moreover, and returning to FIG. 3, one, two, or all of the struts 72L-78L of the low radial stiffness cell(s) 40L can incorporate any of the geometric reductions described above in comparison to the counterpart strut 72E-78E of the elevated stiffness cells 40E.

FIG. 4D illustrates another embodiment low stiffness strut 72L2 in accordance with principles of the present disclosure and that again generally corresponds with the elevated stiffness strut 72E of FIG. 4A. A comparison of FIGS. 4A and 4D reveals that the node 80L2 of the low stiffness strut 72L2 has a reduced height H_(NL2) and width W_(NL2) as compared to the height H_(NE) and width W_(NE) of the elevated stiffness strut 72E. Alternatively, only one of the height H_(NL2) or width W_(NL2) can be reduced. Regardless, the reduction in mass of the node 80L2 effectuates a reduced radial stiffness (as compared to radial stiffness provided by the elevated stiffness strut 72E).

Returning to FIG. 3, in yet other embodiments, the reduced radial stiffness of the first region 60 can be accomplished by forming the connector 70L to have a size less than that associated with the connector 70E of the elevated stiffness second region 62.

The low radial stiffness first region 60 can be generated by a combination of any of the features described above. That is to say, while the closed cells 40L and the connectors 70L of the low radial stiffness first region 60 are generally similar to the closed cells 40E and the connectors 70E of the elevated stiffness second region 62, the reduced radial stiffness is achieved by altering (e.g., reducing) one or more of the strut lengths, widths, node height, node width, degree of taper, and/or connector dimensions. Further, the illustrated size and shape of the elevated stiffness strut 72E, as well as the overall construction of the elevated radial stiffness cells 40E is but one acceptable configuration encompassed by the pending disclosure. A plethora of different strut and/or closed cell shapes, sizes, and patterns are equally acceptable so long as at least one closed cell of the low radial stiffness region 60 incorporates a geometric reduction as compared to the closed cells of the elevated radial stiffness region 62. With embodiments in which more than one band of the stent frame 22 incorporates the varying radial stiffness features (e.g., the first and second bands 50, 52 of FIG. 2A), the low radial stiffness region 60 of longitudinally consecutive bands are aligned and in some embodiments can be similarly constructed. For example, FIG. 2 illustrates the first and second bands 50, 52 as each having the low radial stiffness region 60 (i.e., the low radial stiffness region 60 of the stent frame 22 is optionally collectively defined by struts of two (or more) of the bands 50, 52).

Returning to FIG. 2A, the low radial stiffness region 60 can be located at any longitudinal point along the stent frame 22. In general terms, the low radial stiffness region 60 is arranged at a location corresponding with expected cardiac conductive pathways of the native valve anatomy upon implant. For example, the stent frame 22 of FIG. 2A is configured for implantation at the aortic valve. As described below, conductive pathways are likely to be found along the inflow end 32. Thus, the low radial stiffness region 60 is provided at an anatomic location corresponding with the inflow end 32. Alternatively, the low radial stiffness region 60 can be located anywhere along the stent frame 22, for example at the outflow end 36, or longitudinally between the inflow and outflow ends 32, 36.

With embodiments in which the prosthetic heart valve 20 is intended to be implanted at the aortic valve, certain conductive pathways or fibers naturally occur at the aortic valve and surrounding anatomy. For example, FIG. 5A illustrates the anatomy of an aortic valve and surrounding structures 100 as found in the normal heart. Three valvular leaflets 102L, 102R, 102N are attached across a ventriculoarterial junction 104 in a crown-like fashion running onto either a muscle of the ventricular septum 106 or the mitral valve 108. A left bundle branch 110 emerges at a junction of a membranous septum 112 and right fibrous trigone 114 at the base of the interleaflet triangle between the right and noncoronary leaflets 102R, 102N. The left bundle branch 110 is separated from the aortic valve leaflets 102L, 102R, 102N by the interleaflet triangle. A noncoronary sinus 116, left coronary sinus 118, right coronary sinus 120, sinutubular junction 122, and left fibrous trigone 124 are also identified.

FIG. 5B illustrates the stent frame 22 implanted to the aortic valve 100. The stent frame 22 crosses the ventriculoarterial junction 104 and lies over a region of the left bundle branch 110. In this regard, the low radial stiffness first region 60 is aligned with the left bundle branch 110. As a result, the force exerted by the stent frame 22 on the left bundle branch 110 is reduced (as compared to a conventional configuration in which the band 50 would have a uniform, elevated radial stiffness along the entire circumference and thus apply a high force on to the left bundle branch 110), and is thus less likely to negatively impact the conductive pathways of the heart. In more general terms, depending upon the native valve being repaired, the localized low radial stiffness region 60 is aligned with an expected location of native conduction fibers, several examples of which are identified in FIG. 5C and include the left bundle branch 110, SA node 130, Bundle HIS 132, right bundle branch 134, AV node 136, Purkingee fibers 138, Moderator band 140, and other locations on the conductive pathways of the heart while providing necessary radial resistive force and fatigue strength to maintain long term fixation across the valve being replaced. As a point of reference, the right atrium 150, right ventricle 152, left atrium 154, and left ventricle 156 are also identified in FIG. 5C.

The stented transcatheter prosthetic heart valves of the present disclosure can be delivered to the targeted heart valve in a variety of manners using various transluminal delivery tools as known in the art. In general terms, and with reference to FIG. 6, the prosthetic heart valve 20 is compressed and held within an outer delivery sheath or capsule 200 (referenced generally) and advanced in this compressed condition toward a target site 202. Before deploying the prosthesis 20 (e.g., by retracting the capsule 200 from over the compressed prosthesis 20), the prosthesis 20 is optionally spatially oriented to arrange or align the low radial stiffness region 60 (identified generally with stippling in FIG. 6) with targeted tissue (i.e., where native conductive fibers are expected to reside). In this regard, the stented prosthetic heart valve 20 and/or the capsule 200 can include or carry markers 204 (e.g., radiopaque markers) that correspond with the commissure points 38 (FIG. 1B) of the prosthesis 20. The low radial stiffness region 60 has a known circumferential location relative to the commissure points 38 and thus relative to the markers 204. With an aortic procedure, the markers 204 can then be aligned (e.g., fluoroscopic) with the native commissures between the native noncoronary and right coronary cusps; with this spatial arrangement, the deployed prosthesis 20 will naturally locate the low radial stiffness region 60 over the conductive fibers of the left bundle branch. A variety of other delivery and optional alignment techniques are also envisioned.

Although the present disclosure has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the present disclosure. 

What is claimed is:
 1. A prosthetic heart valve comprising: a stent frame configured to be expandable from a compressed condition for transluminal delivery to a natural, expanded condition, the stent frame having a lattice structure forming a tubular shape defining a circumference, wherein the lattice structure provides a plurality of closed cells arranged to define a plurality of bands including a first band of closed cells extending about an entirety of the circumference, each of the closed cells of the first band being uniformly spaced along the circumference, and further wherein the first band is configured to have a variable radial stiffness along the circumference in the natural condition; wherein the first band defines a first region having at least two circumferentially adjacent closed cells and a second region having a plurality of circumferentially adjacent closed cells, and further wherein a maximum radial stiffness of the first region is less than a minimum radial stiffness of the second region; and a valve structure disposed within a lumen of the stent frame.
 2. The prosthetic heart valve of claim 1, wherein the valve structure includes a plurality of leaflets arranged to define an inflow side and an outflow side, and further wherein the first band is formed proximate the inflow side.
 3. The prosthetic heart valve of claim 1, wherein the first region is configured for alignment over conduction fibers of a left ventricular septum.
 4. The prosthetic heart valve of claim 1, wherein an arc angle of the first region is less than an arc angle of the second region.
 5. The prosthetic heart valve of claim 1, wherein the second region encompasses at least a majority of the circumference.
 6. The prosthetic heart valve of claim 1, wherein each of the closed cells includes a plurality of interconnected struts, and further wherein a geometry of at least one of the struts of the closed cells of the first region is less than a corresponding geometry of a corresponding strut of the closed cells of the second region.
 7. The prosthetic heart valve of claim 6, wherein the geometry is a length of a segment of the strut.
 8. The prosthetic heart valve of claim 6, wherein the geometry is a width of a segment of the strut.
 9. The prosthetic heart valve of claim 6, wherein at least one of the struts at the first region is tapered resulting in a variance in mass of the tapered strut as compared to struts at the second region.
 10. The prosthetic heart valve of claim 1, wherein the first band further includes a joint connector connecting immediately circumferentially adjacent ones of the closed cells to one another, and further wherein a geometry of each of the joint connectors of the first region is less than a corresponding geometry of each of the joint connectors of the second region.
 11. The prosthetic heart valve of claim 10, wherein the geometry is a width of the joint connector.
 12. The prosthetic heart valve of claim 1, wherein the first band further includes a third region having at least one closed cell, and further wherein the third region is circumferentially located between the first and second regions, and even further wherein the radial stiffness of the first band along the third region is less than the radial stiffness along the second region and is greater than the radial stiffness along the first region.
 13. The prosthetic heart valve of claim 12, wherein the first band further includes a fourth region having at least one close cell, the fourth region being circumferentially located between the first and second regions opposite the third region, and further wherein the radial stiffness of the first band along the fourth region approximates the radial stiffness along the third region.
 14. The prosthetic heart valve of claim 1, wherein the plurality of closed cells are arranged to further define a second band of closed cells extending about an entirety of the circumference, the second band being immediately longitudinally adjacent the first band, and further wherein the second band is configured to have a variable radial stiffness along the circumference in the natural condition.
 15. The prosthetic heart valve of claim 14, wherein the first and second bands collectively define a low radial stiffness region.
 16. The prosthetic heart valve of claim 1, wherein the plurality of closed cells are arranged to further define a second band of closed cells extending about an entirety of the circumference, the second band being immediately longitudinally adjacent the first band, and further wherein the second band is configured to have a constant radial stiffness along the circumference.
 17. The prosthetic heart valve of claim 1, wherein the stent frame has first and second ends; wherein each of the cells of the first band are positioned at an equal distance from the first end of the stent frame.
 18. The prosthetic heart valve of claim 1, wherein the first region is adjacent the second region about a single circumference of the stent frame.
 19. The prosthetic heart valve of claim 1, wherein the plurality of closed cells are formed by struts and interconnected with nodes extending between adjacent cells, and further wherein the nodes of the first band are configured to have a variance in mass to result in a variable radial stiffness along the circumference in the natural condition.
 20. A prosthetic heart valve comprising: a stent frame configured to expand from a compressed condition for transluminal delivery to a natural, expanded condition, the stent frame having a first end, a second end, and a lattice structure forming a tubular shape defining a circumference, wherein the lattice structure provides a plurality of closed cells arranged to define first and second bands of closed cells each extending about an entirety of the circumference, the first band located immediately longitudinally adjacent the second band, and further wherein the first band is configured to have a variable radial stiffness along the circumference in the natural condition, and even further wherein each of the closed cells of the second band are directly connected to a corresponding one of the closed cells of the second band; wherein each of the cells of the first band are positioned at an equal distance from the first end of the stent frame; further wherein each of the closed cells includes a plurality of interconnected struts, and at least one of the struts of the first band has a tapered shape; and a valve structure disposed within a lumen of the stent frame.
 21. The prosthetic heart valve of claim 20, wherein the first band defines a first region and a second region; wherein the plurality of closed cells are interconnected at nodes and at least one node of the first region is configured to have a first mass and the nodes of the second region are configured to have a second mass; wherein the first mass is less than the second mass. 